1. Field of the Invention
The present invention relates generally to dental implants and, more particularly, to an improved implant with a zone for soft tissue attachment.
2. Description of the Related Art
Implant dentistry involves the restoration of one or more teeth in a patient""s mouth using artificial components. Such artificial components typically include a dental implant and a prosthetic tooth and/or a final abutment that is secured to the dental implant. Generally, the process for restoring a tooth is carried out in three stages.
Stage I involves implanting the dental implant into the alveolar bone (i.e., jawbone) of a patient. The oral surgeon first accesses the alveolar bone through the patient""s gum tissue and removes any remains of the tooth to be replaced. Next, the specific site in the alveolar bone where the implant will be anchored is widened by drilling and/or reaming to accommodate the width of the dental implant to be implanted. Then, the dental implant is inserted into the hole, typically by screwing, although other techniques are known for introducing the implant in the jawbone.
After the implant is initially installed in the bone, a temporary healing cap is secured over the exposed proximal end in order to seal an internal bore of the implant. The patient""s gums are then sutured over the implant to allow the implant site to heal and to allow desired osseointegration to occur. Complete osseointegration typically takes anywhere from four to ten months.
During stage II, the surgeon reaccesses the implant fixture by making an incision through the patient""s gum tissues. The healing cap is then removed, exposing the proximal end of the implant. Typically, an impression coping in attached to the implant and a mold or impression is then taken of the patient""s mouth to accurately record the position and orientation of the implant within the mouth. This is used to create a plaster model or analogue of the mouth and/or the implant site and provides the information needed to fabricate the prosthetic replacement tooth and any required intermediate prosthetic components. Stage II is typically completed by attaching to the implant a temporary healing abutment or other transmucosal component to control the healing and growth of the patient""s gum tissue around the implant site. In a modified procedure, an abutment or other transmucosal component is either integrally formed with the implant or attached to the implant during stage I. In such a procedure, stages I and II are effectively combined in to a single stage.
Stage III involves fabricating and placement of a cosmetic tooth prosthesis to the implant fixture. The plaster analogue provides laboratory technicians with a model of the patient""s mouth, including the orientation of the implant fixture and/or abutment relative to the surrounding teeth. Based on this model, the technician constructs a final restoration. The final step in the restorative process is replacing the temporary healing abutment with the final abutment and attaching a final prosethesis to the final abutment.
The dental implant is typically fabricated from pure titanium or a titanium alloy. The dental implant typically includes a body portion and a collar. The body portion is configured to extend into and osteointegrate with the alveolar bone. The top surface of the collar typically lies flush with the crest of the jawbone bone. The final abutment typically lies on the top surface and extends through the soft tissue, which lies above the alveolar bone. As mentioned above, the abutment supports the final prostheses. Typically, the coronal or crown portion of the collar and the portions of the final abutment that extend through the soft tissue have a machined or polished surfaces. This arrangement is believed in the art to prevent the accumulation of plaque and calculus and facilitates cleaning.
One aspect of the present invention includes the recognition that the body""s natural defense mechanisms tend to provide approximately a 2-3 millimeter zone of soft tissue between the abutment-implant interface (i.e., microgap) and the alveolar crest. This zone is referred to as the xe2x80x9cbiological widthxe2x80x9d and is present around natural teeth as well as dental implants. The biological width typically extends 360 degrees around the implant and lies coronal to the alveolar crest and apical to the prosthetic crown margin (approximately 2.5-3 millimeters). The biological width consists of approximately 1 millimeter gingival sulcus, 1 millimeter epithelial attachment and 1 millimeter connective tissue attachment. In prior art implants, the abutment-implant interface typically lies flush with the alveolar crest. As such, the bone tissue is reabsorbed and the alveolar crest retreats until the proper biological width can be reestablished. This bone loss is undesirable both aesthetically and structurally.
Another aspect of the present invention includes the recognition that the smooth surfaces of the collar and the abutment tend to inhibit the attachment of connective soft tissues. Accordingly, bone tissue is reabsorbed and the soft tissue and alveolar crest typically move a distance down of approximately 1-2 millimeters from the smooth surfaces of the collar and/or abutment. As mentioned above, such bone loss is undesirable.
Yet another aspect of the invention is the recognition that in the prior art typically provides for a flat interface (i.e., microgap) between the abutment and the collar of the implant. However, due to the irregular configuration of the alveolar crest, a flat interface makes it difficult to conform to a proper biological width in all 360 degrees around the implant. A proper biological width that does not extend for all 360 degrees around the implant can produce undesirable bone loss.
One aspect of the present invention provides for a one piece dental implant, which has a roughened surface which extends above the alveolar crest. This roughened surface allows connective tissue to attach to the implant. In one application of the invention, the coronal portion above the alveolar crest of the collar and implant is prepared similar to a natural tooth by providing approximately 360 degrees of at least about a 2 millimeter zone of roughened surface above the alveolar crest. Preferably, the implant is provided with approximately 360 degrees of at least a 3 millimeter zone of roughened surface above the alveolar crest. More preferably, the implant is provided with approximately 360 degrees of at least a 4 millimeter zone of roughed surface above the alveolar crest. In modified arrangements, the dental implant comprises more than once piece while still providing approximately 360 degrees of 2-4 millimeters or more of roughened surface above the alveolar crest.
Still yet another aspect of the invention is a method for installing a dental prosthesis into a patient""s mouth. A dental implant is provided. The dental implant include a body portion at a distal end of the dental implant, an abutment portion at a proximal end of the dental implant and a collar portion located between the body portion and the abutment portion. The collar portion includes an outer surface with a tissue attachment portion, which preferably is roughened. The dental implant is installed into the patient""s jawbone such that the body portion lies substantially beneath a crest of a patient""s jawbone and the tissue attachment portion of the collar portion extends above the crest of a patient""s jawbone. In some arrangements, the tissue attachment portion extends from the top of the patient""s gums to the crest of the patient""s jawbone. In other arrangements, the tissue attachment portion extends from the final restoration to the crest of the patient""s jawbone.
The tissue attachment zone preferably covers at least 50% of the surface between the crest of the patient""s jawbone and the proximal edge of the tissue attachment zone. More preferably, the tissue attachment zone covers at least 75% of this surface. In other applications, the tissue attachment zone covers at least 90% of this surface. Most preferably, the soft tissue attachment zone covers 100% of the surface between the crest of the jawbone and proximal edge of the soft tissue attachment zone.
For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed.